CN114122409B - Pole pieces and lithium-ion batteries - Google Patents

Abstract

The embodiment of the application provides a pole piece and lithium ion battery, this pole piece includes current collector layer, semiconductor layer and alkali metal supplement layer, the semiconductor layer set up in at least one surface on current collector layer, alkali metal supplement layer is mending lithium agent layer or mending sodium agent layer, alkali metal supplement layer set up in the semiconductor layer keep away from one side on current collector layer. The pole piece provided by the embodiment of the application avoids the reaction caused by direct contact between the alkali metal supplement layer and the battery electrode material when the pole piece is pressed by arranging the semiconductor layer between the current collector layer and the alkali metal supplement layer. In addition, the semiconductor layer can flexibly control the on-off of the semiconductor layer according to the adjustment of the triggering condition of the semiconductor layer, so that the supplementing rate and the supplementing quantity of the pole piece are controlled, and the lithium supplementing flexibility of the lithium ion battery is improved.

Description

Pole pieces and lithium-ion batteries

Technical field

This application relates to the technical field of battery equipment. Specifically, this application relates to a pole piece and a lithium-ion battery.

Background technique

In recent years, with the continuous improvement of people's environmental awareness, electric vehicles have gradually replaced fuel vehicles and become the most popular among users. In the process of continuous upgrading of electric vehicles, lithium-ion batteries, as the main power components of electric vehicles, have put forward higher requirements for the energy density, cycle life and other performance of lithium-ion batteries.

During the first charge and discharge process of a lithium-ion battery, active lithium ions are consumed due to the solid electrolyte interface film (SEI) formed on the negative electrode, resulting in a significant reduction in the capacity of the lithium-ion battery. The Coulombic efficiency of the first charge and discharge of a lithium-ion battery using graphite as the negative electrode is approximately 92-94%, the first Coulombic efficiency of lithium-ion batteries using silicon carbon as the negative electrode was only 75-85%.

At present, the capacity of lithium-ion batteries is mainly increased through pre-lithium replenishment technology. Specifically, the lithium replenishment agent can be dispersed or added to the pole piece and made into a battery. The battery can be activated by charging and discharging cycles, and then the lithium replenishing agent can be added to the pole piece. The active lithium ions contained in the lithium replenishing agent on the chip are released, thereby making up for the active lithium lost due to the film formation of the lithium-ion battery, thereby increasing the capacity of the lithium-ion battery. However, this method of lithium supplementation is generally a one-time lithium supplementation and cannot effectively control the lithium supplementation process.

Contents of the invention

Embodiments of the present application provide a pole piece and a lithium-ion battery to solve the problem of difficulty in effectively controlling the lithium replenishment process of existing lithium-ion batteries.

In order to solve the above problems, the embodiments of this application adopt the following technical solutions:

In a first aspect, embodiments of the present application provide a pole piece, including:

current collector layer;

A semiconductor layer, the semiconductor layer is provided on at least one surface of the current collector layer;

Alkali metal supplementary layer, the alkali metal supplementary layer is a lithium supplementary agent layer or a sodium supplementary agent layer, and the alkali metal supplementary layer is provided on the side of the semiconductor layer away from the current collector layer.

Optionally, the thickness of the alkali metal supplementary layer ranges from 50-300um.

Optionally, the alkali metal replenishing layer is a lithium replenishing agent layer, and the lithium replenishing agent layer is a negative electrode lithium replenishing agent layer.

Optionally, the negative electrode lithium replenishing agent layer includes at least one of metallic lithium, lithium silicon alloy, lithium aluminum alloy, lithium boron alloy and lithium magnesium alloy.

Optionally, the alkali metal replenishing layer is a lithium replenishing agent layer, and the lithium replenishing agent layer is a positive electrode lithium replenishing agent layer.

Optionally, the positive electrode lithium replenishing agent layer includes at least one of lithium oxide, lithium ferrite, lithium cobalt oxide and lithium nickelate.

Optionally, the area resistance of the semiconductor layer ranges from 10 ^-3 to 10 ⁵ mΩ·m ² .

Optionally, the thickness of the semiconductor layer ranges from 100 to 500 nm.

In a second aspect, embodiments of the present application provide a lithium-ion battery, including a positive electrode sheet, a negative electrode sheet and the electrode sheet described in the first aspect, and the alkali metal supplementary layer is a lithium supplementary agent layer;

The positive electrode piece and the negative electrode piece are separated from each other by a separator, and at least one of the electrode pieces is separated from the positive electrode piece and/or the negative electrode piece by the separator.

Optionally, the pole piece is a negative pole piece, and the pole piece includes a lithium-supplementing tab extending from the current collector layer. The negative electrode piece includes a negative electrode tab, and the lithium-supplementing tab is connected to the lithium-supplementing tab. Negative lug connection.

Optionally, the pole piece is a positive pole piece, the pole piece includes a lithium-supplementing tab, the positive electrode piece includes a positive tab, and the lithium-supplementing tab is connected to the positive tab.

The technical solutions adopted in the embodiments of this application can achieve the following beneficial effects:

Embodiments of the present application provide a pole piece, including a current collector layer, a semiconductor layer and an alkali metal supplementary layer. The semiconductor layer is provided on at least one surface of the current collector layer. The alkali metal supplementary layer is a lithium replenishing agent. layer or sodium supplement layer, the alkali metal supplement layer is provided on the side of the semiconductor layer away from the current collector layer. By disposing the semiconductor layer between the current collector layer and the alkali metal supplementary layer, the pole piece provided by the embodiment of the present application can flexibly control the on-off of the semiconductor layer according to the adjustment of the triggering conditions of the semiconductor layer, thereby improving the efficiency of the pole piece. Controllability of the pole pieces.

Description of the drawings

The drawings described here are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation of the present application. In the attached picture:

Figure 1 is a schematic structural diagram of a pole piece provided by an embodiment of the present application;

Figure 2 is a schematic structural diagram of a lithium-ion battery provided by an embodiment of the present application;

Figure 3 is a comparison chart of the capacity test curves of a lithium-ion battery before and after lithium replenishment provided by the embodiment of the present application;

Figure 4 is a comparison chart of cycle test curves of a lithium-ion battery before and after lithium replenishment provided by the embodiment of the present application.

Explanation of reference symbols:

1-pole piece; 101-current collector layer; 102-semiconductor layer; 103-alkali metal supplementary layer; 2-positive electrode piece; 3-negative electrode piece; 4-separator.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions of the present application will be clearly and completely described below in conjunction with specific embodiments of the present application and corresponding drawings. Obviously, the described embodiments are only some of the embodiments of the present application, but not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

The terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects and are not used to describe a specific order or sequence. It is to be understood that the figures so used are interchangeable under appropriate circumstances so that the embodiments of the present application can be practiced in orders other than those illustrated or described herein, and that "first," "second," etc. are distinguished Objects are usually of one type, and the number of objects is not limited. For example, the first object can be one or multiple. In addition, "and/or" in the description and claims indicates at least one of the connected objects, and the character "/" generally indicates that the related objects are in an "or" relationship.

The technical solutions disclosed in various embodiments of the present application will be described in detail below with reference to the accompanying drawings.

Referring to Figure 1, an embodiment of the present application provides a pole piece 1, including:

Current collector layer 101, semiconductor layer 102 and alkali metal supplementary layer 103. The semiconductor layer 102 is provided on at least one surface of the current collector layer 101. Specifically, the semiconductor layer 102 may be provided on a surface of the current collector layer 101. One side surface may also be the surface on which the semiconductor layer 102 is disposed on both sides of the current collector layer 101; the alkali metal supplementary layer 103 is a lithium replenishing agent layer or a sodium replenishing agent layer. The alkali metal replenishing layer 103 Disposed on the side of the semiconductor layer 102 away from the current collector layer 101 . The semiconductor layer 102 has a large resistivity under normal conditions, and there is no conduction between the current collector layer 1012 and the alkali metal supplementary layer 103. When the semiconductor layer 102 is triggered under high temperature or high pressure conditions, the semiconductor layer The resistance of 102 is significantly reduced, and the current collector layer 101 and the alkali metal supplementary layer 103 are connected. At this time, a path can be formed between the current collector layer 101 and the alkali metal supplementary layer 103. The alkali metal supplementary layer After the active alkali metal in the layer 103 is released, it replenishes the positive electrode sheet or the negative electrode sheet that needs to be replenished with alkali metal, and the replenishment rate and replenishment of the alkali metal replenishment layer 103 can be flexibly controlled according to the trigger condition adjustment of the semiconductor layer 102 quantity.

The pole piece 1 provided by the embodiment of the present application disposes the semiconductor layer 102 between the current collector layer 101 and the alkali metal supplementary layer 103 to avoid the contact between the alkali metal supplementary layer 103 and the battery electrode when the pole piece 1 is pressed. Materials react by direct contact with each other. More importantly, the semiconductor layer 102 can flexibly control the on and off of the semiconductor layer 102 according to the adjustment of its triggering conditions, and control the pole pieces through battery SOC (System on Chip) status, battery temperature or internal pressure control. The rate and amount of active ions released in 1 are thereby controlled, and the replenishment rate and amount of the pole piece 1 are controlled, thereby improving the flexibility of the pole piece 1 .

In addition, the flexible switching of the semiconductor layer 102 realizes a controllable lithium or sodium replenishment process to a certain extent, and can realize the release of active lithium or active lithium or active materials into lithium-ion batteries or sodium-ion batteries in stages and batches as needed. Sodium allows the battery's active alkali metal to be replenished in time after it is lost, greatly improving the battery's cycle performance. Therefore, the triggering of the semiconductor layer 102 may include a first triggering stage and a second triggering stage. The first triggering stage and the second triggering stage not only include only two triggering stages, but the semiconductor layer 102 may also include multiple triggering stages. This supplementary stage can be realized as long as the pole piece 1 still contains active alkali metal and the semiconductor layer 102 is conductive.

Optionally, the thickness of the alkali metal supplementary layer 103 ranges from 50-300um, preferably 125-200um.

Specifically, the thickness of the alkali metal supplementary layer 103 is directly related to the replenishment times and replenishment amount of the pole piece 1. If the alkali metal replenishment layer 103 is too thin, the replenishment amount of the pole piece 1 may not reach The replenishment needs of the battery's positive electrode plate or negative electrode plate, or the electrode plate 1 can only be replenished a few times, cannot meet the long-term lithium replenishment needs of the battery. However, if the alkali metal supplementary layer 103 is too thick, it may cause waste and occupy too much space of the battery.

Optionally, the alkali metal replenishing layer is a lithium replenishing agent layer, and the lithium replenishing agent layer is a negative electrode lithium replenishing agent layer.

Specifically, when the alkali metal replenishing layer 103 is a negative electrode lithium replenishing agent layer, the negative electrode lithium replenishing agent layer may include at least one of metal lithium, lithium silicon alloy, lithium aluminum alloy, lithium boron alloy and lithium magnesium alloy. . Metal lithium can be ultra-thin lithium ribbons, stabilized metal lithium powder or lithium flakes. In this case, the current collector layer 101 may be a copper foil, and the semiconductor layer 102 is disposed between the negative electrode lithium replenishing agent layer and the copper foil. The pole piece 1 can be connected to the negative electrode piece of the lithium ion battery. When the semiconductor layer 102 is turned on, the pole piece 1 can replenish lithium for the negative electrode piece.

Optionally, the alkali metal replenishing layer 103 is a lithium replenishing agent layer, and the lithium replenishing agent layer is a positive electrode lithium replenishing agent layer.

Specifically, when the alkali metal supplement layer 103 is a positive electrode lithium supplement layer, the positive electrode lithium supplement layer may include at least one of lithium oxide, lithium ferrite, lithium cobalt oxide, and lithium nickelate. In this case, the current collector layer 101 may be an aluminum foil, and the semiconductor layer 102 is disposed between the positive electrode lithium replenishing agent layer and the aluminum foil. The pole piece 1 can be connected to the positive electrode piece of the lithium ion battery. When the semiconductor layer 102 is turned on, the pole piece 1 can replenish lithium for the positive electrode piece.

Optionally, the surface resistance of the semiconductor layer 102 ranges from 10 ^-3 to 10 ⁵ mΩ·m ² . This can further ensure the flexible switching of the semiconductor layer 102 and achieve controllable lithium or sodium supplementation.

Specifically, the semiconductor layer 102 may be a heat-sensitive semiconductor, and the heat-sensitive semiconductor may be oxidized by one of ZnO, CuO, NiO, Al ₂ O ₃ , Fe ₂ O ₃ , Mn ₃ O ₄ and Co ₃ O ₄ Obtained from compounds or multiple oxides. When the semiconductor layer 102 is a heat-sensitive semiconductor, its on-off state can be controlled by controlling the temperature of the semiconductor layer 102 . Specifically, when the temperature of the semiconductor layer 102 is low or at normal temperature, the surface resistance of the semiconductor layer 102 is large, which can separate the current collector layer 101 and the alkali metal supplementary layer 103; the semiconductor layer 102 When the temperature is high, the surface resistance of the semiconductor layer 102 is significantly reduced, and the current collector layer 101 and the alkali metal replenishing layer 103 are connected, which can realize the replenishing process of the pole piece 1 and achieve flexible control. Describe the role of pole piece 1 supplement. When the temperature of the semiconductor layer 102 is low or the surface resistance at room temperature is too large, it is difficult for the semiconductor layer 102 to reach a conductive state after the temperature rises, which is inconvenient for the replenishment process of the pole piece 1 . When the temperature of the semiconductor layer 102 is low or the surface resistance at normal temperature is too small, a large self-discharge may occur, which cannot effectively control the on-off function of the semiconductor layer 102; if the semiconductor layer 102 is heated after heating, If the surface resistance of 102 is too small, the conduction of the semiconductor layer 102 does not require an obvious heating process, which may cause the semiconductor layer 102 to be in a conductive state for a long time, and the flexible control of the pole piece 1 cannot be achieved. For the purpose of supplementation, if the surface resistance of the semiconductor layer 102 is too large after the temperature rises, it will be difficult for the semiconductor layer 102 to reach a conductive state after the temperature rises, and it will also be inconvenient to realize the replenishment process of the pole piece 1 .

In a specific implementation, by adjusting the composition of the material of the semiconductor layer 102 and the thickness of the coating of the semiconductor layer 102, the sheet resistance of the coating of the semiconductor layer 102 is maintained at 10 ^-3 to 10 ⁵ between mΩ·m ² . When the semiconductor layer 102 is in a disconnected state at room temperature, the surface resistance of the semiconductor layer 102 can reach 10 ⁵ mΩ·m ² , both sides of the semiconductor layer 102 are basically electronically insulated, and the leakage current is less than 0.1 μA/m ² ; When the semiconductor layer 102 is in a high-temperature conduction state, for example, when the internal temperature of the lithium-ion battery is 60°C, the surface resistance of the coating of the semiconductor layer 102 is less than 10 ^-3 mΩ·m ² . At this time, the The electrons on both sides of the coating of the semiconductor layer 102 are conductive, and the pole piece 1 can replenish lithium or sodium for the battery pole piece. In addition, the semiconductor layer 102 can also be a pressure-sensitive semiconductor. A pressure control component is provided inside the lithium-ion battery, and the pressure control component can control the on-off of the pressure-sensitive semiconductor.

Optionally, the thickness of the semiconductor layer 102 ranges from 100 to 500 nm, preferably from 180 to 350 nm.

Specifically, when the semiconductor layer 102 is not triggered to conduct, that is, when the semiconductor layer 102 is disconnected, the resistance of the semiconductor layer 102 is very high, so the thickness of the semiconductor layer 102 only needs to be A few hundred nanometers can effectively block the electron exchange between the current collector layer 101 and the alkali metal supplementary layer 103 . When the semiconductor layer 102 is too thick, it not only causes waste, but also occupies the limited space inside the battery.

Referring to Figure 2, embodiments of the present application also provide a lithium ion battery, including a positive electrode piece 2, a negative electrode piece 3 and the electrode piece 1; the alkali metal supplementary layer 103 of the electrode piece 1 is a lithium replenishing agent layer, the positive electrode sheet 2 and the negative electrode sheet 3 are separated from each other by a separator 4 , and at least one of the pole sheets 1 is separated from the positive electrode sheet 2 and/or the negative electrode sheet 3 by the separator 4 .

Specifically, by arranging the semiconductor layer 102 between the current collector layer 101 and the alkali metal supplementary layer 103 of the pole piece 1, the alkali metal supplementary layer 103 avoids contact with the negative electrode of the battery when the pole piece 1 is pressed. Materials react with each other to produce heat. At the same time, after the electrolyte is injected into the lithium-ion battery, the alkali metal supplementary layer 103 will not react violently with the negative electrode material of the battery to produce SEI film residue, which reduces the risk of lithium precipitation in the lithium-ion battery. In addition, when the alkali metal supplement layer 103 of the electrode piece 1 is a sodium supplement layer, the positive electrode piece 2, the negative electrode piece 3 and the electrode piece 1 can adopt a structure similar to the above-mentioned lithium ion battery. to prepare sodium-ion batteries.

More importantly, the flexible switching of the semiconductor layer 102 realizes a controllable pre-lithiation process to a certain extent, and can release active lithium to the lithium-ion battery in stages and batches as needed, so that the lithium-ion battery is active. Lithium can be replenished in time after loss, which greatly improves the cycle performance of lithium-ion batteries and extends the service life of lithium-ion batteries.

Optionally, the pole piece 1 is a negative pole piece, and the pole piece 1 includes a lithium-supplementing tab extending from the current collector layer 101. The negative electrode piece 3 includes a negative tab, and the lithium-supplementing tab The ear is connected to the negative ear.

Specifically, the number of the pole pieces 1 may be one, two, three or more, the number of the negative pole pieces 3 may also be one, two, three or more, and multiple pole pieces The lithium-supplementing tab of 1 is connected to the negative tabs of a plurality of negative electrode sheets 3. When the semiconductor layer 102 is conductive, a path is formed between the pole sheet 1 and the negative electrode sheet 3. The pole piece 1 can replenish lithium to the negative pole piece 3; when the negative pole piece 3 does not need to replenish lithium, the lithium replenishment path can be disconnected by disconnecting the semiconductor layer 102.

In a specific implementation, referring to Figure 2, in a lithium-ion battery, the number of the electrode pieces 1 is two, the number of the positive electrode pieces 2 and the negative electrode pieces 3 is multiple, and a plurality of the Positive electrode sheets 2 and negative electrode sheets 3 are alternately arranged and separated by the separator 4. The upper and lower sides of the lithium ion battery are provided with electrode sheets 1 close to the negative electrode sheets 3. The negative electrode sheets 3 and the electrode sheets 1 are separated by the diaphragm 4, and the lithium replenishing tabs of two pole pieces 1 are connected to the negative pole tabs of a plurality of negative pole pieces 3, so that the pole pieces 1 can replenish the negative pole pieces 3. lithium.

Optionally, the pole piece 1 is a positive pole piece, and the pole piece 1 includes a lithium-supplementing tab, and the positive electrode piece 2 includes a positive tab, and the lithium-supplementing tab is connected to the positive tab.

Specifically, the number of the pole pieces 1 can be one, two, three or more, the number of the positive pole pieces 2 can also be one, two, three or more, and multiple pole pieces The lithium-supplementing tabs of 1 are connected to the positive tabs of multiple positive electrode sheets 2. When the semiconductor layer 102 is conductive, a path is formed between the pole sheet 1 and the positive electrode sheet 2. The pole piece 1 can replenish lithium to the positive pole piece 2; when the positive pole piece 2 does not need to replenish lithium, the lithium replenishment path can be disconnected by disconnecting the semiconductor layer 102.

This application describes the pole piece and the lithium-ion battery containing it through the following specific examples:

Pole piece embodiment 1

The pole piece includes:

Copper foil current collector, a dense semiconductor layer is set on the surface of the copper foil. The semiconductor layer is a heat-sensitive material with a thickness of 100nm. The formula (mass ratio) is ZnO:NiO:Al ₂ O ₃ :Fe ₂ O ₃ =0.3 :0.3:0.3:0.1, the area resistance of the semiconductor layer at 25℃ is 2.3*10 ⁴ mΩ·m ² , and the area resistance of the semiconductor layer at 60℃ is 2.6*10 ^-3 mΩ·m ² ; An alkali metal supplementary layer is provided on the side of the semiconductor layer away from the copper foil. The thickness of the alkali metal supplementary layer is 50 μm.

Pole piece embodiment 2

The pole piece includes:

Copper foil current collector, a dense semiconductor layer is set on the surface of the copper foil. The semiconductor layer is a heat-sensitive material with a thickness of 500nm. The formula (mass ratio) is ZnO:NiO:Al ₂ O ₃ :Fe ₂ O ₃ =0.4 :0.4:0.1:0.1, the area resistance of the semiconductor layer at 25℃ is 9*10 ⁴ mΩ·m ² , and the area resistance of the semiconductor layer at 60℃ is 1.6*10 ^-2 mΩ·m ² ; An alkali metal supplementary layer is provided on the side of the semiconductor layer away from the copper foil. The thickness of the alkali metal supplementary layer is 300 μm.

Pole piece embodiment 3

The pole piece includes:

For the copper foil current collector, a dense semiconductor layer is provided on the surface of the copper foil. The semiconductor layer is a heat-sensitive material with a thickness of 180nm. The formula (mass ratio) is ZnO:NiO:Al ₂ O ₃ =0.4:0.4:0.2. The surface resistance of the semiconductor layer at 25℃ is 6.3*10 ⁴ mΩ·m ² , and the surface resistance of the semiconductor layer at 60℃ is 1.0*10 ^-3 mΩ·m ² ; keep the semiconductor layer away from the copper foil An alkali metal supplementary layer is provided on one side, and the thickness of the alkali metal supplementary layer is 125 μm.

Pole piece embodiment 4

The pole piece includes:

Copper foil current collector, a dense semiconductor layer is set on the surface of the copper foil. The semiconductor layer is a heat-sensitive material with a thickness of 350nm. The formula (mass ratio) is ZnO:NiO:Al ₂ O ₃ :Fe ₂ O ₃ =0.25 ^{; _ _ _} An alkali metal supplementary layer is provided on the side of the semiconductor layer away from the copper foil. The thickness of the alkali metal supplementary layer is 200 μm.

Pole piece embodiment 5

The pole piece includes:

Copper foil current collector, a dense semiconductor layer is set on the surface of the copper foil. The semiconductor layer is a heat-sensitive material with a thickness of 250nm. The formula (mass ratio) is ZnO:NiO:Al ₂ O ₃ :Fe ₂ O ₃ =0.2 :0.3:0.2:0.3, the area resistance of the semiconductor layer at 25℃ is 8.5*10 ⁴ mΩ·m ² , and the area resistance of the semiconductor layer at 60℃ is 1.7*10 ^-3 mΩ·m ² ; An alkali metal supplementary layer is provided on the side of the semiconductor layer away from the copper foil. The thickness of the alkali metal supplementary layer is 200 μm.

Pole piece embodiment 6

The pole piece includes:

Copper foil current collector, a dense semiconductor layer is set on the surface of the copper foil. The semiconductor layer is a heat-sensitive material with a thickness of 50nm. The formula (mass ratio) is ZnO:NiO:Al ₂ O ₃ :Fe ₂ O ₃ =0.2 :0.3:0.2:0.3, the area resistance of the semiconductor layer at 25℃ is 4.5*10 ³ mΩ·m ² , and the area resistance of the semiconductor layer at 60℃ is 3.9*10 ^-4 mΩ·m ² ; An alkali metal supplementary layer is provided on the side of the semiconductor layer away from the copper foil. The thickness of the alkali metal supplementary layer is 50 μm.

Pole piece embodiment 7

The pole piece includes:

Copper foil current collector, a dense semiconductor layer is set on the surface of the copper foil. The semiconductor layer is a heat-sensitive material with a thickness of 100nm. The formula (mass ratio) is ZnO:NiO:Al ₂ O ₃ :Fe ₂ O ₃ =0.2 :0.3:0.2:0.3, the area resistance of the semiconductor layer at 25℃ is 3.2*10 ⁴ mΩ·m ² , and the area resistance of the semiconductor layer at 60℃ is 6.8*10 ^-3 mΩ·m ² ; An alkali metal supplementary layer is provided on the side of the semiconductor layer away from the copper foil. The thickness of the alkali metal supplementary layer is 30 μm.

Pole piece embodiment 8

The pole piece includes:

Copper foil current collector, a dense semiconductor layer is set on the surface of the copper foil. The semiconductor layer is a heat-sensitive material with a thickness of 600nm. The formula (mass ratio) is ZnO:NiO:Al ₂ O ₃ :Fe ₂ O ₃ =0.2 :0.3:0.2:0.3, the area resistance of the semiconductor layer at 25℃ is 9.2*10 ⁴ mΩ·m ² , and the area resistance of the semiconductor layer at 60℃ is 8.8*10 ^-3 mΩ·m ² ; An alkali metal supplementary layer is provided on the side of the semiconductor layer away from the copper foil. The thickness of the alkali metal supplementary layer is 50 μm.

Pole piece embodiment 9

The pole piece includes:

Copper foil current collector, a dense semiconductor layer is set on the surface of the copper foil. The semiconductor layer is a heat-sensitive material with a thickness of 100nm. The formula (mass ratio) is ZnO:NiO:Al ₂ O ₃ :Fe ₂ O ₃ =0.2 :0.3:0.2:0.3, the area resistance of the semiconductor layer at 25℃ is 2.4*10 ⁴ mΩ·m ² , and the area resistance of the semiconductor layer at 60℃ is 1.2*10 ^-3 mΩ·m ² ; An alkali metal supplementary layer is provided on the side of the semiconductor layer away from the copper foil. The thickness of the alkali metal supplementary layer is 400 μm.

Pole piece comparison example 1

Traditional lithium tape, the thickness of the lithium tape is 50μm.

In this application, the pole pieces of the above-mentioned embodiments 1 to 9 are added as independent electrodes to the laminated cells of the lithium-ion battery. The positive electrode of the laminated cell is lithium iron phosphate, and the positive electrode surface density is 400g/m. ² , the compacted density is 2.60g/m ³ , the negative electrode is natural graphite, the negative electrode surface density is 205g/m ² , the negative electrode compacted density is 1.55g/m ³ , the number of laminated layers (the number of pairs of positive and negative electrode sheets) for 30 floors. Lithium ion battery Examples 1 to 9 were obtained. The traditional lithium belt in Example 1 was directly rolled onto the laminated cell negative electrode of the lithium ion battery as the lithium ion battery Comparative Example 1, and no pole piece was added. The above-mentioned lithium-ion battery is used as Comparative Example 2. The activation and testing process of the above-mentioned lithium-ion battery is carried out. The specific instructions are as follows:

Activation process: Divide the lithium-ion battery into its content at room temperature, then adjust the SOC state of the lithium-ion battery to 0%. At this time, the open circuit voltage of the lithium-ion battery is in the range of 2.45-2.55V, and then heat the lithium-ion battery to After high temperature infiltration at 45°C for 12 hours, the semiconductor layer of the pole piece conducts electricity, and a path is formed between the alkali metal supplementary layer and the current collector layer. At this time, the active lithium in the alkali metal supplementary layer will be detached from the pole piece and embedded into the lithium ion battery. in the graphite negative electrode. By monitoring the voltage of the lithium-ion battery, the lithium supplement amount of the pole piece is controlled and adjusted. When the open circuit voltage of the lithium-ion battery rises by 0.2V, the lithium-ion battery can be cooled to 25°C to complete the activation process. The activation process is usually within 8 -12h or so, (Comparative Example 1 and Comparative Example 2 do not need to go through the activation process).

Capacity test: At room temperature, charge the activated lithium-ion battery to 3.8V under 0.1C constant current and constant voltage conditions, let it stand for 30 minutes, then discharge it to 2.0V at 0.1C constant current condition, let it stand for 30 minutes, and the above process Repeat three times to obtain a stable discharge capacity.

Cycle test: At room temperature, charge the activated lithium-ion battery to 3.8V at a constant current and voltage of 0.33C, let it stand for 30 minutes, then discharge it at a constant current of 0.33C to 2.0V, let it stand for 30 minutes, and repeat the above process for 2000 Second-rate. Among them, a capacity test is performed every 100 cycles.

Storage test: Charge the activated lithium-ion battery to 100% SOC for storage at room temperature, and conduct a capacity test every other week.

Table 1 shows the lithium-ion battery test results of Examples 1 to 9 and Comparative Examples 1 and 2. It can be seen from Table 1 that the lithium-ion batteries provided in Examples 1 to 5 of this application are the first to The charge and discharge capacity can reach more than 150mAh/g, the capacity retention rate can still reach more than 88.3% after 2000 charge and discharge cycles, and the capacity retention rate can still reach more than 98.4 after 26 weeks of storage. Moreover, the capacity retention rate of the lithium-ion battery obtained in Example 4 can even reach more than 90% after 2000 cycles of charge and discharge, and the capacity retention rate can be around 100% after 26 weeks of storage, indicating that the capacity of the lithium-ion battery has basically not decayed after long-term storage. .

When the thickness of the semiconductor layer or the thickness of the alkali metal supplementary layer in Examples 6 to 9 is lower than the range of the preferred embodiments of the present application, or higher than the range of the preferred embodiments of the present application, the first charge and discharge capacity of the lithium ion battery can only be reaches below 150.6mAh/g, but can still remain above 143.2mAh/g. The capacity retention rate is 80%-85% after 2000 charge and discharge cycles, and the capacity retention rate is in the range of 93%-96% after 26 weeks of storage. Although they are lower than the lithium-ion batteries provided in Examples 1 to 5 of the present application, they can still maintain relatively high capacity and retention rate.

In Comparative Examples 1 and 2, the first charge and discharge capacities of the lithium-ion batteries obtained by using traditional lithium belts with and without lithium supplementation were 143.2mAh/g and 135.5mAh/g respectively, and the capacity retention rate after 2000 charge and discharge cycles was About 80%, the capacity retention rates after 26 weeks of storage are both lower than 93.5%, which are significantly lower than the lithium-ion batteries provided in the embodiments of the present application. Moreover, the first charge and discharge capacity of the lithium-ion battery obtained without lithium supplementation is significantly lower than the first charge and discharge capacity of the lithium-ion battery obtained after lithium supplementation.

Table 1 Lithium-ion battery test results

Figures 3 and 4 show a comparison of the capacity test curves and cycle test curves of the lithium-ion battery in Example 1 after lithium replenishment and Comparative Example 2 without lithium replenishment. From Figures 3 and 4 and Table 1 It can be seen from the data in that the capacity of the lithium-ion battery 5 after lithium supplementation in Example 1 is improved by 12% compared to the lithium-ion battery without lithium supplementation in Comparative Example 2, and the cycle performance of the lithium-ion battery 5 after lithium supplementation is compared with that of the lithium-ion battery 5 after supplementation. Lithium-ion batteries improve by 10% @2000cycles. After lithium replenishment, the capacity of lithium-ion battery 5 only dropped by 9.4% after 26 weeks of storage at room temperature.

The embodiments of the present application have been described above in conjunction with the accompanying drawings. However, the present application is not limited to the above-mentioned specific implementations. The above-mentioned specific implementations are only illustrative and not restrictive. Those of ordinary skill in the art will Inspired by this application, many forms can be made without departing from the purpose of this application and the scope protected by the claims, all of which fall within the protection of this application.

Claims (11)

1. A pole piece (1), characterized in that it includes: Current collector layer (101); Semiconductor layer (102), the semiconductor layer (102) is provided on at least one surface of the current collector layer (101); Alkali metal supplementary layer (103), the alkali metal supplementary layer (103) is a lithium supplementary agent layer or a sodium supplementary agent layer, the alkali metal supplementary layer (103) is arranged on the semiconductor layer (102) away from the assembly One side of the fluid layer (101); Wherein, the semiconductor layer (102) can be turned on and off to control the release of active alkali metal in the alkali metal supplementary layer (103); The semiconductor layer (102) is a heat-sensitive semiconductor or a pressure-sensitive semiconductor; When the semiconductor layer (102) is a heat-sensitive semiconductor, the heat-sensitive semiconductor is made of one of ZnO, CuO, NiO, Al ₂ O ₃ , Fe ₂ O ₃ , Mn ₃ O ₄ and Co ₃ O ₄ Oxides or combinations of multiple oxides. 2. The pole piece (1) according to claim 1, characterized in that the thickness of the alkali metal supplementary layer (103) ranges from 50-300um. 3. The pole piece (1) according to claim 1, characterized in that the alkali metal replenishing layer (103) is a lithium replenishing agent layer, and the lithium replenishing agent layer is a negative electrode lithium replenishing agent layer. 4. The pole piece (1) according to claim 3, characterized in that the negative electrode lithium replenishing agent layer includes at least one of metallic lithium, lithium silicon alloy, lithium aluminum alloy, lithium boron alloy and lithium magnesium alloy. . 5. The pole piece (1) according to claim 1, characterized in that the alkali metal replenishing layer (103) is a lithium replenishing agent layer, and the lithium replenishing agent layer is a positive electrode lithium replenishing agent layer. 6. The pole piece (1) according to claim 5, characterized in that the positive electrode lithium replenishing agent layer includes at least one of lithium oxide, lithium ferrite, lithium cobalt oxide and lithium nickel oxide. 7. The pole piece (1) according to claim 1, characterized in that the area resistance of the semiconductor layer (102) ranges from 10 ^-3 to 10 ⁵ mΩ·m ² . 8. The pole piece (1) according to claim 7, characterized in that the thickness of the semiconductor layer (102) ranges from 100 to 500 nm. 9. A lithium ion battery, characterized in that it includes a positive electrode sheet (2), a negative electrode sheet (3) and the electrode sheet (1) according to any one of claims 1 to 8, and the alkali metal supplementary layer (103 ) is the lithium supplement layer; The positive electrode sheet (2) and the negative electrode sheet (3) are separated from each other by a separator (4), and at least one of the pole sheets (1) is connected to the positive electrode sheet (2) and/or the positive electrode sheet (2) through the separator (4). The negative electrode piece (3) is separated. 10. The lithium ion battery according to claim 9, characterized in that the pole piece (1) is a negative pole piece, and the pole piece (1) includes a pole extending from the current collector layer (101). Lithium-supplementing tab, the negative electrode piece (3) includes a negative tab, and the lithium-supplementing tab is connected to the negative tab. 11. The lithium-ion battery according to claim 9, characterized in that the pole piece (1) is a positive pole piece, the pole piece (1) includes a lithium replenishing tab, and the positive electrode piece (2) includes Positive electrode tab, the lithium replenishing electrode tab is connected to the positive electrode tab.